Preparation, Characterization, and Kinetic Study of a Core–Shell Mn3O4@SiO2Nanostructure Catalyst for CO Oxidation

Mn 3 O 4 @SiO 2 prepared via a Stöber route showed a steady reaction rate for CO oxidation at 250 °C after 12 h. The reaction orders, with respect to CO (0.49–0.12) and O 2 (0.4–0.6), were obtained for a Mn 3 O 4 @SiO 2 catalyst ( d Mn 3 O 4 = 7.6 nm) in the temperature range of 220–280 °C. Via Operando Raman spectroscopy, a CO ad -induced change in the symmetric stretch of Mn–O–Mn (from 636 cm –1 to 642 cm –1 ) was observed for Mn 3 O 4 @SiO 2, indicating a tiny structure modification of core Mn 3 O 4 by the adsorption of CO. With the combination of the catalyst structure and the kinetics of CO oxidation, we assume that this reaction proceeds mainly through the Langmuir–Hinshelwood mechanism at or below 280 °C. In comparison with the reference α-Mn 2 O 3 catalyst, the presence of shell SiO 2 does not change the reaction behavior but improves the catalyst stability.